Paleontologists Uncover Oldest Species of Bone-Headed Dinosaur in North America

Paleontologists have uncovered a new species of bone-headed dinosaur. Now, they've found out that this plant-eating dinosaur represents the oldest of its kind in North America--and possibly the world.

Named Acrotholus audeti, the dinosaur's remains were partially discovered on a ranch in Canada in 2008. The six-foot-long dinosaur once roamed the Earth about 85 million years ago, prowling the ground on two legs. Its large, dome-shaped head was used for display to other members of its species. In fact, some researchers believe that it could have been used in head-butting contests--rather like how deer put on displays in contests for females during the spring.

Yet actually discovering the dinosaur wasn't easy. The finding is based on two skull "caps" from the Milk River Formation of southern Alberta in Canada. While one was collected by the Royal Ontario Museum over 50 years ago, the other, better specimen was only recently unearthed in 2008. Now, researchers are learning a little bit more about this plant-eating dinosaur by studying its remains.

"Acrotholus provides a wealth of new information on the evolution of bone-headed dinosaurs," said lead author David Evans in a news release. "Although it is one of the earliest known members of this group, its thickened skull dome is surprisingly well-developed for its geological age. More importantly, the unique fossil record of these animals suggests that we are only beginning to understand the diversity of small-bodied plant-eating dinosaurs."

While the dome is intriguing, though, the dinosaur's skeleton is what has scientists interested. The domes are usually relatively well-preserved since they're made out of a solid piece of bone. The rest of the skeleton, in contrast, is relatively delicate--rather like the bones of other small, plant-eating dinosaurs. It's therefore possible that these dinosaurs could lead to a better understanding of the diversity of plant-eating dinosaurs as a whole.

"We can predict that many new small dinosaur species like Acrotholus are waiting to be discovered by researchers willing to sort through the many small bones that they pick up in the field," said co-author Michael Ryan in a news release.

The findings of this study are published in the journal Nature Communications.